Typically, combustible solid waste is introduced into a thermal treatment furnace, such as an incinerator, in its original form or after being reduced in size by a shredder-type device. The moisture content of the waste particles is usually “as-received” and the smallest practical size achieved by a conventional shredder is several centimeters.
Efforts have also been made in the past to convert waste materials, such as waste paper products, into useful forms, including fuel. One such method is disclosed in U.S. Pat. No. 4,123,489 where paper waste is processed by a rotary cutter which includes a knife cylinder having a plurality of blades for cutting the waste paper products fed into the machine into smaller pieces or particles. The cutter includes a recutter screen having a surface cooperating with the periphery of the rotating knife cylinder, providing sizing openings for further reducing the size of the pieces of paper waste. The pieces passing through the recutter screen are cut to a maximum of ⅛ inch by 2 inches which makes the material suitable for various purposes, including feeding into the die cavity of a pelletizing machine to form high quality, relatively dust-free pellets of paper material, that can be used as a fuel. Such pellets, however, do not constitute a very efficient fuel since their surface to mass ratio is not very high.
There is thus a need for the conversion of solid combustible waste into a highly efficient fuel that can be readily used, for example, in a plasma fired eductor or any other combustion reactor.